The present invention relates to the semiconductor manufacturing equipment. More specifically, the present invention relates to the implantation of rare-earth ions into ceramic materials and using the implanted material for selected ceramic components of such semiconductor manufacturing equipment.
Because of their physical characteristics, ceramic materials are commonly used in today""s semiconductor manufacturing equipment to meet the high standards of process performance demanded by integrated circuit manufacturers. Ceramic materials present higher resistance to corrosion, help increasing process kit lifetimes and lower the cost of consumables as compared to materials such as aluminum or quartz which have been commonly used in the past. Some common components that can be advantageously manufactured from ceramic materials include chamber domes for inductively coupled reactors, edge rings used to confine deposition gases to the upper surface of a substrate in some processing chambers and chamber liners that protect the walls from direct contact with a plasma formed within the chamber and improve plasma confinement by reducing the coupling of a plasma with conductive chamber walls. Ceramic materials are also used for critical components, such as high temperature heaters and electrostatic chucks among others.
While the particle generation caused by aging and corrosion is much improved for ceramic parts as compared to anodized or coated parts, it remains a critical problem for high temperature applications (e.g., applications where processing temperatures are greater than 550xc2x0 C.). Indeed, the corrosion of Al2O3 and AlN ceramics in highly corrosive fluorine and chlorine environments may result in the formation of AlO:F, AlFx and AlClx films at the surface of the ceramic component. These films have relatively high vapor pressures and relatively low sublimation temperatures (e.g., the sublimation temperature of aluminum chloride is approximately 350xc2x0 C. and the sublimation temperature of aluminum fluoride is approximately 600xc2x0 C.) and can attain thicknesses of several hundred micrometers when conditions for self-passivation are not met. If a particular ceramic component (e.g., heater, electrostatic chuck, cover plate, etc.) is used above the sublimation temperature, the outer surface of the component is consumed during the process in which the AlO:F, AlFx or AlClx film is formed. Furthermore, it has been observed, that under ion bombardment, an AlF film can be sputtered, even at temperatures less than 400xc2x0 C. This phenomenon may result in recondensation of the byproducts on colder components (e.g., showerheads and chamber liners) and may lead to process drift and particle contamination in some substrate processing chambers.
With the development of high density plasma sources, the development of 300 mm-wafer-size reactors and the growing importance of certain high temperature processing steps, the wear of chamber materials and its impact on the tool performance and productivity are challenged. Specifically, the interaction of corrosive plasmas and reactor materials become of critical importance to the development of future product lines of semiconductor manufacturing equipment. Very harsh environments (e.g., NF3, C2F6, C3F3, ClF3, CF4, SiH4, TEOS, WF6, NH3, HBr, etc.) can be found in plasma etchers and plasma-enhanced deposition reactors. Constituents from many of these environments may react with and corrode ceramic materials such as aluminum nitride and aluminum oxide. Therefore, the combination of long plasma exposure times, high temperature processes and high plasma densities are revealing problems never encountered.
In light of the above, improvements in the corrosion resistance of various substrate processing chamber parts and components are desirable. Ideally, critical ceramic parts, such as high temperature heaters (heaters for use at temperatures greater than 550xc2x0 C.) and electrostatic chucks (ESC), should have a lifetime of at least one year on a production tool. Depending on the tool chamber, this can correspond to processing 50,000 wafers or more without having to change any parts of the tool (i.e., a zero consumable situation) while maintaining high standards of process performance. For example, to meet some manufacturer""s requirements, the number of particles added on the wafer during the deposition of certain dielectric films must be less than 20 at a particle size of greater than 0.2 xcexcm.
The present invention provides a method for improving the corrosion resistance of critical ceramic parts by implanting the parts with rare-earth ions. The implanted ceramic parts are highly resistant to corrosive environments that can be formed in semiconductor manufacturing equipment including those found in high temperature applications and high density plasma applications.
In a preferred embodiment of the method of the present invention, the ceramic parts are implanted with rare-earth ions using an implantation technique based on a metal vapor vacuum arc (MEVVA(trademark)) ion source. The MEVVA(trademark) source provides very high ion beam current (up to several amperes) for rapid, industrially-scalable, ceramic parts surface treatment. Rare earth (RE) ions are used for implantation because during substrate processing in a highly corrosive environment a rare-earth fluoride material, RE:F3, may form at the surface of the ceramic component. The sublimation temperature of such a RE:F3 layer is much higher than that of layers such as AlF3 that are formed on standard ceramic chamber components (e.g., up to 1100xc2x0 C. as compared to 600xc2x0 C.). At substrate processing temperatures less than the sublimation temperature, the formed RE:F3 layer acts as a passivation layer preventing consumption of the ceramic part during further substrate processing.
According to the apparatus of the present invention, a substrate processing chamber including at least one component implanted with rare-earth ions is provided. In various specific embodiments, the rare-earth-ion-implanted ceramic component is one or more of a chamber liner, a chamber dome, a cover plate, a gas manifold or faceplate and/or a substrate holder, such as a high temperature heater or an electrostatic chuck.
These and other embodiments of the present invention, as well as its advantages and features, are described in more detail in conjunction with the text below and attached figures.